diff --git a/src/sql/workbench/contrib/notebook/browser/notebookActions.ts b/src/sql/workbench/contrib/notebook/browser/notebookActions.ts
index e6c64290d0..dbfc43df4e 100644
--- a/src/sql/workbench/contrib/notebook/browser/notebookActions.ts
+++ b/src/sql/workbench/contrib/notebook/browser/notebookActions.ts
@@ -80,9 +80,12 @@ export class AddCellAction extends Action {
 				context.model.sendNotebookTelemetryActionEvent(TelemetryKeys.NbTelemetryAction.AddCell, { cell_type: this.cellType });
 			}
 		} else {
-			//Add Cell after current selected cell.
+			// Add cell after currently selected cell, or at the end of the notebook if no cell is selected
 			const editor = this._notebookService.findNotebookEditor(context);
-			const index = editor.cells?.findIndex(cell => cell.active) ?? 0;
+			if (editor.cells) {
+				let currentCellIndex = editor.cells.findIndex(cell => cell.active);
+				index = currentCellIndex !== -1 ? currentCellIndex + 1 : editor.cells.length;
+			}
 			editor.addCell(this.cellType, index);
 			editor.model.sendNotebookTelemetryActionEvent(TelemetryKeys.NbTelemetryAction.AddCell, { cell_type: this.cellType });
 		}